1. Field of the Invention
The invention relates to crashworthy passenger seats for fixed wing aircraft, and in particular to rearwardly facing two-man passenger seats.
2. Description of the Prior Art
Recently it has become recognized that numerous unnecessary fatalities have occurred in crashes of fixed-wing aircraft, both commercial and military. Investigation and research disclose that these fatilities are primarily caused by the "second impact" which occurs in such crashes. The "second impact" is that impact following the impact of the aircraft with the ground or some other object, which consists of the collision of the passenger with a fixed member of the aircraft, such as a bulkhead. Such "second impacts" are primarily, caused by the separation of the passenger seat from its connection with the floor of the aircraft and its subsequent travel at high speeds, terminating in a collision of the passenger seat and passenger with the fixed member of the aircraft.
Through a number of systems exist for rendering crashworthy the passenger seats of military and commercial rotary wing aircraft, such as the system described and claimed in U.S. Pat. No. 4,150,805 to applicant, these systems do not have ready application in the context of the fixed wing aircraft. The crashes have different profiles with respect to time and force, as well as components of the crash. In connection with crashes of rotary wing aircraft, the crash pulses tend to be more vertical in direction with sharper onset accelerations and shorter total crash times as opposed to fixed wing aircraft which have longer crash times, smaller vertical component of crash, and smaller onset acceleration.
Existing systems for rendering crashworthy passenger seats of fixed wing aircraft suffer from the significant infirmity that the seats are inadequately connected to the floor of the aircraft, thus resulting in detaching thereof under most crash conditions with the consequence of the "second impact" noted above. A primary problem affecting existing passenger seats for fixed wing aircraft is that of distortion of the floor of the aircraft under crash conditions. Due to the requirement for lightweight materials in the structural members of aircraft, such structural members are of necessity not massive and extremely rigid. Under crash conditions, such structures, including the floor of the aircraft, flex significantly. A consequence of such flexing is detachment of existing passenger seats from the vibrating floor. Existing seat attachments in fixed wing aircraft do not have sufficient rigidity or energy absorption capabilities to perform adequately under such conditions of crash-induced floor distortion.
Thus, there has been felt but unfulfilled need for a system for providing crashworthy passenger seats in military and commercial fixed wing aircraft, which will be adaptable to a number of different contexts in the military and commercial areas and will furnish at the same time a maximum of safety for the passengers utilizing such crashworthy seats.